Systemic inflammation and multiple organ failure associated with trauma are a major cause of mortality and morbidity in American soldiers and veterans. Gut barrier dysfunction plays a critical role in the development of posttraumatic complications such as sepsis by providing the major site for plasma leakage and bacterial translocation to the circulation. Despite the well- recognized importance of gut dysfunction in the pathogenesis of posttraumatic complications, the intestinal permeability response to severe burns, a major form of trauma, has not been well characterized, and its cellular and molecular mechanisms remain poorly understood. The goal of this study is to elucidate the cell-specific mechanisms of leaky guts during thermal injury. We propose to define the function, regulation and molecular mechanisms of palmitoylation in mediating gut epithelial hyperpermeability during thermal injury. The hypothesis to be tested is that burn injury stimulates protein palmitoylation in the gut epithelial cells through upregulation of DHHC isoforms. Palmitoylation contributes to the pathogenesis of burn-induced gut hyperpermeability by stimulating ROCK-dependent cytoskeleton contraction and claudins/ZO2- mediated junction dissociation in the epithelial cells leading to epithelial barrier failure. Three specific aims are developed in this proposal to: 1) study the function and regulation of palmitoylation in gut epithelial barrier injury, 2). examine the regulatory role of palmitoylation n gut epithelium during thermal injury, and 3) identify molecular targets of palmitoylation in mediating epithelial hyperpermeability. The study design employs complimentary in vivo, ex vivo, and in vitro models that incorporate molecular and genetic approaches into physiological experiments under clinically relevant trauma conditions. The significance of this study lies in the potential to identify a new role of protein palmitoylation in pathogenesis during trauma. Data derived from the research work will not only contribute to the advancement of gastrointestinal pathobiology, but also has clinical implications in the development of effective therapies or surgical interventions against gut barrier injury in patients with trauma or inflammatory diseases.